Dietary Nitrates & Exercise Performance: Influence of Training Status
Faculty Advisor Name
Dr. Nick Luden
Department
Department of Kinesiology
Description
The aim of this study is to determine if peak oxygen consumption (VO2peak)influences the responsiveness to dietary nitrate supplementation (i.e., changes in nitric oxide availability, oxygen cost and exercise performance), and further, to elucidate how this correlates to their training intensity and volumes. Eleven male and three female cyclists between 18 and 45 years of age were recruited. This study is part of a larger study in which the influence of beetroot juice (BRJ) on performance at simulated altitude was also assessed. As a result, this randomized, double-blind, placebo-controlled experiment included four, seven-day experimental phases. For the BRJ trials, subjects consumed 140 milliliters (ml) of concentrated beetroot juice [Beet It; James White Drinks, containing 12.8 millimole (mmol) nitrates] each day for three days (day 5, 6, and 7 of each phase). For the first two days, this dose was separated into a morning and afternoon dose (70 ml each). The final 140 ml dose was consumed three hours prior to the exercise trials, detailed below. For the placebo (PL) trials, subjects consumed 140 ml of nitrate-depleted beetroot juice (James White Drinks, containing 0 mmol nitrates) at the same time points. An incremental cycling test starting at 50 Watts (W) and increasing by 25 W/minute was performed until volitional fatigue during a preliminary trial to assess VO2peak and to determine cycling workloads (Wmax) for the experimental trials. VO2peak was used as one of the criteria to categorize participants as moderately trained cyclists [< 55 ml/kilogram (kg)/minute (min)], or highly trained cyclists (> 60 ml/kg/min). Following the preliminary trial, subjects completed a familiarization trial where participants replicated the VO2peak test described above in the alternative altitude condition to the preliminary test and performed the exercise procedures described below, without supplementation, resting measures, and 10 minutes of constant load cycling at 45% Wmax. On day 7 of each trial phase subjects reported to the Human Performance Lab where upon arrival, subjects rested for 5 minutes and received an expired nitric oxide measurement, blood pressure measurement and blood draw. Following these measurements, they consumed their final supplements, left the laboratory, and returned two and a half hours later. Upon returning, subjects received the same resting measures followed by 20 minutes of constant load cycling; 10 min at 45% and 10 min at 65% Wmax at 80-100 revolutions per minute. Following constant load exercise subjects completed a simulated 4-kilometer time trial as quickly as possible. All experimental trials involved participants breathing through a mask connected to an altitude tent connected to two hypoxic generators. During normoxic trials, inspired air was not modified and in hypoxic conditions, the inspired oxygen was reduced to 15.3%.
Dietary Nitrates & Exercise Performance: Influence of Training Status
The aim of this study is to determine if peak oxygen consumption (VO2peak)influences the responsiveness to dietary nitrate supplementation (i.e., changes in nitric oxide availability, oxygen cost and exercise performance), and further, to elucidate how this correlates to their training intensity and volumes. Eleven male and three female cyclists between 18 and 45 years of age were recruited. This study is part of a larger study in which the influence of beetroot juice (BRJ) on performance at simulated altitude was also assessed. As a result, this randomized, double-blind, placebo-controlled experiment included four, seven-day experimental phases. For the BRJ trials, subjects consumed 140 milliliters (ml) of concentrated beetroot juice [Beet It; James White Drinks, containing 12.8 millimole (mmol) nitrates] each day for three days (day 5, 6, and 7 of each phase). For the first two days, this dose was separated into a morning and afternoon dose (70 ml each). The final 140 ml dose was consumed three hours prior to the exercise trials, detailed below. For the placebo (PL) trials, subjects consumed 140 ml of nitrate-depleted beetroot juice (James White Drinks, containing 0 mmol nitrates) at the same time points. An incremental cycling test starting at 50 Watts (W) and increasing by 25 W/minute was performed until volitional fatigue during a preliminary trial to assess VO2peak and to determine cycling workloads (Wmax) for the experimental trials. VO2peak was used as one of the criteria to categorize participants as moderately trained cyclists [< 55 ml/kilogram (kg)/minute (min)], or highly trained cyclists (> 60 ml/kg/min). Following the preliminary trial, subjects completed a familiarization trial where participants replicated the VO2peak test described above in the alternative altitude condition to the preliminary test and performed the exercise procedures described below, without supplementation, resting measures, and 10 minutes of constant load cycling at 45% Wmax. On day 7 of each trial phase subjects reported to the Human Performance Lab where upon arrival, subjects rested for 5 minutes and received an expired nitric oxide measurement, blood pressure measurement and blood draw. Following these measurements, they consumed their final supplements, left the laboratory, and returned two and a half hours later. Upon returning, subjects received the same resting measures followed by 20 minutes of constant load cycling; 10 min at 45% and 10 min at 65% Wmax at 80-100 revolutions per minute. Following constant load exercise subjects completed a simulated 4-kilometer time trial as quickly as possible. All experimental trials involved participants breathing through a mask connected to an altitude tent connected to two hypoxic generators. During normoxic trials, inspired air was not modified and in hypoxic conditions, the inspired oxygen was reduced to 15.3%.
